A 12 V, 60 W lamp is connected to the secondary of a step down transformer, whose primary is connected to ac mains of 220 V. Assuming the transformer to be ideal, what is the current in the primary winding?

1. 0.37 A

2. 0.27 A

3. 2.7 A

4. 3.7 A

Doubtly Asked 30 Oct 2026 NEET UG 2023 Practice test neet Save WhatsApp Report

1 answer

Best answer

Answer: 2. 0.27 A

An ideal transformer has no loss, so input power equals output power.

Output power = 60 W, so \(V_pI_p = 60\Rightarrow I_p=\dfrac{60}{220}\approx 0.27\) A.

The answer is 0.27 A. (3.7 A or 2.7 A come from wrong powers of ten; 0.37 A would need about 81 W.)

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

Was this answer helpful?